There is a technical service bulletin for the V8 engines regarding a possible problem with the spark plug being ejected from the cylinder head, damaging the threads in the spark plug hole. If the vehicle is under warranty, cylinder head replacement is recommended. If the vehicle is out of warranty, Ford authorized the use of a specific thread insert to repair the head.

Intermittent rough idle may be caused by the EGR sensor sticking, causing the EGR valve to stay slightly open. Our technicians tell us the valve and sensor must be replaced together to correct this concern.

Hard starts, long crank time before the start, rough idle, and loss
of power can be caused by using the wrong type of oil in this motor.
With the engine off, remove the oil dipstick and inspect. If tiny
bubbles are present, then the oil is foaming and unable to maintain
proper operating pressure in the high pressure oil system.

When changing the fuel filter, if the fuel in the filter bowl looks gray or black, it may be a sign that the fuel injector O-rings are allowing high pressure oil to migrate into the fuel return system. Symptoms of this are rough idle or hard starting.